Bernard j. Beaudoin
Chairman of the Board President and
Chief Executive Officer
January 28, 2002
The Honorable George Voinovich
Committee on Environment and Public Works United States Senate
Washington, D.C. 20510
Dear Senator Voinovich:
Thank you for inviting Kansas City Power & Light to comment on provisions in S. 556, the Clean Power Act of 2001, to address mercury emissions from coal-fired electric generating units and the technology currently available to address such emissions.
Kansas City Power & Light is the second largest investor owned electric utility in Missouri, with 70 percent of its more than 3,733 megawatt generation capacity being coal-fired. The remainder of Kansas City Power & Light's generation is made up of nuclear, natural gas and oil.
At the outset, let me say that Kansas City Power & Light supports a multi-emissions strategy that imposes reasonable emissions reductions of sulfur dioxide, nitrogen oxides, and mercury under timeframes that allow us to achieve such reductions in a cost-effective manner. In our view, this approach should allow "co-benefits" for mercury control through installation of currently available technology to remove emissions of sulfur dioxide, nitrogen oxides and particulate matter rather than impose a rigid 90 percent source specific reduction mandate. We firmly believe a co-benefits approach can achieve real environmental benefits while providing our company and other companies a degree of business certainty in the foreseeable future.
The treatment of mercury emissions under S. 556 and a recent proposal by the Environmental Protection Agency (EP A) is a significant concern to Kansas City Power & Light because we use western low sulfur subbituminous coal. Mercury emissions from low sulfur subbituminous coal are lower and in a form, known as "elemental" mercury, which is extremely difficult to remove, a fact with which virtually everyone, including EPA, agrees.
The amount of mercury emitted from a coal-fired power plant is impacted by a number of factors, including the type of coal being fired, boiler design and operation, fly ash characteristics, and associated environmental controls. Estimates of mercury removal are made even more difficult due to the large volumes of gas to be treated, low concentrations of mercury, and the presence of difficult to capture species such as elemental mercury.
The capture of mercury by flue gas cleaning devices is dependent on the chemical and physical forms of mercury. Factors that affect the speciation and capture of mercury in coal-fired combustion systems include the type and properties of the coal, the combustion conditions, the type of flue gas cleaning technologies employed, and the temperatures at which the flue gas cleaning systems operate. There are three basic forms of mercury in the flue gas from coal combustion: elemental mercury (Hg˚), ionic mercury [Hg(II)], and particulate-bound mercury [Hg(p)].
Both Hg˚ and Hg(II) are in the vapor phase at flue gas cleaning temperatures. Hg˚ is insoluble in water and cannot be captured in wet scrubbers.
To comply with the provisions of S. 556, taking into account proven commercially available control equipment currently available, each coal-fired unit in the United States would be required to install a scrubber system for sulfur dioxide. Selective catalytic reduction for nitrogen oxides, and a fabric filter for particulate control.
Currently there is no proven or demonstrated technology to control mercury emissions. There is evidence, however, based on experience in Europe and the Electric Power Research Institute's (EPRI) bench scale studies, that mercury can be co-beneficially removed by air pollution control equipment required to comply with other Clean Air Act requirements, i.e., wet (flue gas desulfurization, also known as FGD) or dry scrubber systems (SDA) for suČlfur dioxide (S02) control, selective catalytic reduction (SCR or SNCR) for nitrogen oxides (NOx), and fabric filters or baghouses for capture of particulate matter (PM).
After a thorough study of the research information presently available, KCPL is confident that any coal- fired unit equipped with SCR, SDA, and fabric filters, as would be required by S. 556, will achieve the maximum degree of reduction in emissions of mercury through co-benefits, taking into consideration the costs of achieving such emission reduction, any non-air quality health and environmental impacts, and energy requirements associated with the emission reduction.
The level of control of mercury through co-benefits is based on several assumptions:
These assumptions are based on the limited amount of research data available, and presume that the EPRI research studies and analyses from Phase ill of EPA 's Information Collection Request (ICR) are correct and applicable.
At an August 200l meeting, an EPA official observed that SCR and SNCR might improve mercury removal. This confirmed the utility industry's position that the use of post-combustion NOx controls such as SCR and SNCR may enhance oxidation of Hg˚ to Hg(II) and thus result in the co-benefit of increased mercury removal in FGD systems.
EPA's analyses from Phase III of its ICR provide mercury removal efficiencies of existing air pollution control equipment as shown in the attached chart.
EPA and industry appear to agree that there are presently two pri~ technologies that could be considered in establishing a regulatory standard for mercury. They are co-control with FGD and powdered activated carbon injection.
The injection of powdered activated carbon or other absorbents upstream of a particulate control device is one of the most promising methods for controlling mercury emissions from existing utility boilers equipped only with electrostatic precipitators (ESPs) or fabric filters. The key statement is controlling mercury emissions from existing utility boilers equipped only with electrostatic precipitators or fabric filters. Should S. 556 be enacted in its present form, each coal-fired unit in the United States will be required to install a scrubber system for sulfur dioxide control, selective catalytic reduction for nitrogen oxides, and a fabric filter for particulate control. This therefore would negate any benefit to be achieved because utility boilers would not be equipped only with electrostatic precipitators or fabric filters.
A number of studies carried out at bench, pilot, and full-scale levels have examined the influence of carbon type, carbon structure, carbon surface chemistry, injection method (dry or wet), amount of carbon injected, and flue gas temperature on mercury removal. Results indicate that a wide variety of factors influence the mercury removal obtained with sorbent injection upstream of an ESP or fabric filter baghouse. These factors include the mercury species being removed (oxidized vs. elemental), the flue gas composition, process conditions (e.g., temperature), sorbent characteristics (e.g., size), and the presence of other active surfaces (e.g., fly ash). Results also show that although general trends between different sorbents and test conditions exist, sorbent performance tends to be site specific and depends on the exact nature of the flue gas at a particular site.
Based on review of the available information, a new unit firing subbituminous coal, which produces primarily elemental mercury (the hardest form to remove), equipped with SCR, SDA, and a fabric filter, may not realize any additional mercury removal due to the addition of powdered activated carbon or other dry sorbent injection. This is of great concern to Kansas City Power & Light because we just rebuilt a 550 megawatt unit, our Hawthorn 5 facility, using a state-of-the-art combination of SCR, dry scrubber and fabric filter and burning low sulfur subbituminous coal. This combination of equipment and fuel, making Hawthorn 5 the cleanest coal-fired power plant in the country, may be able to achieve a 45 percent level of mercury reduction based on currently available information.
We therefore urge the Committee to develop a more flexible legislative approach to mercury that recognizes the limited effectiveness of state-of-the-art technology in removing elemental mercury from flue gas emissions. Until there are better technological advances, we believe the Committee should allow a co-benefits approach to mercury.
We appreciate your good work on this important issue. We encourage you to continue your efforts to balance an outcome that will protect the environment and a reliable and affordable supply of electricity throughout the country.
ATTACHMENT: Mean Mercury Emission Reductions for PC-Fired Boilers table_KCP&L.gif